Calorimetric analysis of lipid-sterol systems: a comparison between structurally similar cholesterol and vitamin D3 interacting with phospholipid bilayers of different thickness
✍ Scribed by Antonio Raudino; Francesco Castelli; Maria Grazia Sarpietro; Antonio Cambria
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 864 KB
- Volume
- 74
- Category
- Article
- ISSN
- 0009-3084
No coin nor oath required. For personal study only.
✦ Synopsis
We compared the thermotropic properties (transition temperatures and associated enthalpies) of phosphatidylcholine (PC) bilayers of varying chain length containing either cholesterol or vitamin D 3. The two sterols are structurally similar but behave in rather different ways. Both transition temperature and associated enthalpy decrease on raising the amount of sterol dissolved in the lipid matrix; the decrease, however, depends on the PC's chain length and is markedly different for cholesterol and vitamin D 3. These differences have been rationalized on the basis of a simple theoretical model by employing a mean field statistical thermodynamics approach. The model has been developed in a perturbation scheme by considering cholesterol as reference molecule and vitamin D 3 as a slightly modified cholesterol. Taking together experimental and theoretical results, we infer that the different thermotropic behavior of the two sterols is mainly due to (a) weaker PC-vitamin D 3 pair interactions as compared with PCcholesterol and (b) greater ability of cholesterol to reduce the co-operative melting of PC lipid chains.